Rotatable thread take-up device for sewing machines



YROTATABLE mam: TAKE-UP DEVICE FOR smwmc MACHINES Filed m 19, 1958 E. MOSINSKI Jan. 12, 1960 5 Sheets-Sheet 1 INVENTUR Erik/1 MOS/N51! Jan. 12, 1960 E. MOSINSKI 7 2,920,591

ROTATABLE THREAD TAKE-UP DEVICE FOR SEWING MACHINES Filed llay 19, 1958 a Sheets-Sheet 2 INVE N TOP [rich M06/N6KI E. MOSINSKI Jan. 12, 1960 ROTATABLE THREAD TAKE-UP DEVICE FOR SEWING MACHINES Filed May 19, 1958 '3 Sheets-Sheet 3 United States Patent O ROTATABLE THREAD TAKE-UP DEVICE FOR SEWING MACHINES Erich Mosinski, Kaiserslautern, Pfalz, Germany, assignor to G. M. Pfaif A.G., Kaiserslantern, Pfalz, Germany Application May 19, 1958, Serial No. 736,171

1 Claims priority, application Germany May 28, 1957 Claims. '(Cl. 112248) The invention relates to sewing machines, particularly to thread take-up devices for sewing machines.

More in particular, the invention relates to rotatable thread take-up devices for sewing machines where stationary thread guides, in combination with rotatable thread guides moving at identical angular velocity along coaxial circular paths, define a periodically changing length of the path of the thread. Such thread guides are particularly advantageous because in such guides only a rigid unitary structure ismovable, which requires no lubrication except for its journalling which may simultaneously be that of the main shaft of the machine.

Thread take-up devices of this type known heretofore do not operate satisfactorily, especially at high numbers of revolution, because the released length of thread cannot readily be adapted to the thread requirements 'at any given moment. This results in disadvantages.

For the better explanation of the invention the curve of the thread requirements which depends on the movement of the needle bar is referred to as thread need curve, and the curve showing the length of path required thread is seized by rapidly rotating parts and carried along. Another possibility is that the thread released by the thread take-up is insufficient at any instant for making available the thread requirement determined by the particular position of the looper at a particular time, so that even before the moment at which the stitch is to be tightened the thread follow up takes place through the thread tensioning device. As a consequence, the thread tension for pulling in the stitch is lacking at the right moment. It may also happen that shortly after the lowermost dead point position of the needle, the loop formation is endangered by lack of thread. Therefore, a good approximation of the thread feed characteristic to the thread requirement curve is also of greatest importance.

It is an object of the invention to realize with the simplest possible means and in a most thread protecting manner a desired thread feed characteristic by arranging the guiding means in such a manner that at least one rotating guide during one rotation influences in succession the length of two sections of the path of the thread, each extending between two fixed thread guides. This can be effected in that the thread path sections to be acted upon in succession are each disposed between two fixed thread guides in a plane extending perpendicularly to the axis of rotation of the take-up, the connecting lines between which intersect outside of the largest circle of the course of the rotating thread guides acting on the thread path sections.

In accordance with a further object of the invention a thread loop, constituted of two thread path sections each extending between two fixed thread guides and acted upon by rotating thread guides, envelops two rotating new thread take-up illustrated in the accompanying drawings in which:

Fig. 1 is. a perspective view of the head of a sewing machine provided with the rotating thread take-up,

Fig. 2 shows the thread take-up with the cover plate removed in the position where the length of the thread path is shortest,

Fig. 3 is a view similar to Fig. 2 indicating the position of the device at the moment when the eye of the needle enters the material,

Fig. 4 is a section through the thread take-up showing parts thereof in displaced angular position,

Fig. 5 illustrates the arrangement and relationship of the rotating and fixed thread guides, and

Fig. 6 is the thread need curve and the thread feed characteristic of the thread take-up illustrated.

The head 1 of the machine (Figs. 1 and 4) supports in a known manner the material presser bar 2 as well as the needle bar 3, where the reciprocating movements of the needle bar are derived in a known manner from the main shaft by way of the needle bar drive member 4, crank pin 5 and the crank 6. The lower portion of the front end of the machine head 1 is closed by the cover plate 8 which supports a thread tensioning device 9 of conventional construction and a guide strip 10 for the thread. 7

In the upper portion of the front end of the head 1 a circular opening 11 is provided which accommodates a disk 13 secured by means of screws 12 to the crank pin 5. This disk, in turn rigidly supports a disk 15 secured thereto by means of screws 14 and having connected thereto an annular disk 18 by means of rotatable thread guides 16, 17 which suitably have a longitudinal cross section extending in the direction of the axis of rotation substantially perpendicularly thereto. The annular disk, in turn, supports a further rotatable thread guide in the form of a pin 19. The construction and arrangement of the rotatable thread guides 16, 17 and 19 can best be seen in Fig. 5, while for a better general illustration they are shown angularly displaced with respect to one another in Fig. 4. It will be apparent that a rigid unitary structure is connected to the crank pin 5, comprising the components 13 to 19 and which has no sliding parts and is, therefore, adapted to operate without any lubrication whatsoever.

A stationary annular plate 20 is mounted in the plane of the rotatable annular disk 18, which is secured to the head 1 by means which simultaneously serve as stationary thread guides 21 and 22. The thread guide 21 is in the form of a pin which is riveted to annular plate 20 and is secured in a bore of head 1 by means of a set screw 23 as shown in Fig. 4, while the thread guide 22 is defined by a spacing roller disposed over the shaft of a fastening screw 24. The annular disk 20 is provided with a slot 25 and also with a further thread guide 26 in the form of a hook. A fixedly disposed thread guide 28 of cylindrical shape having an internal threaded portion and a pair of abutments 27, which together with a screw 29 serves for fastening a cover plate 30 projects through a recess in the annular plate 20 at the front end of the head 1. The abutments 27 project into recesses in the cover plate 30 to safeguard against turning. The cover plate has a central circular aperture 31 as well as a recessed annular groove 32 for the rotatable thread guide 19. A thread engaging thethread guide 19 is protected in this manner against slipping ofi laterally.

The thread is placed on the thread take-up in the following manner. Upon being pulled through the thread guide 33 and through the thread tensioning mechanism 9, the thread is brought around the guide strip 10 whereupon it is-introduced into the slot between the annular,

plate 20 and the front end of thehead 1 andbeginni-ng at the fixed thread guide 28 it is looped counter-clockwise around the axis of rotation of the thread take-up. By introducing the thread into the slot '25 the thread end is then brought into the plane between the annular plate 20 and the cover plate '30, whereupon it is conducted further by means of another counter-clockwise turn which causes it to slide over a further thread guide 26 which is in the form of a hook. n moving the thread back it jumps into the hook because the hook has an open end on its right side which extends somewhat into a recess in the annular plate 20. From here the thread is guided in a known manner up to the needle.

- In explanation of the manner of operation the thread need or requirement curve and the thread feed characteristic are illustrated in Fig. 6. The angular position a of the main shaft is chosen as the abscissa and the starting position is the upper dead point of the needle bar. The thread need or requirement I for a particular looper position corresponding to a predetermined position of the main shaft is entered as the ordinate in the curve of broken lines while the negative values of the length of the thread path I determined by the thread take-up is illustrated in full lines as the thread take-up characteristic. The reference line for both curves is chosen in such a manner that at the moment where the stitch is fully pulled in they are both zero.

During sewing the unitary structure of the thread takeup or feeder which is constituted of parts 13 to 19 rotates in clockwise direction. In Fig. 2 the length of the thread path determined by the fixed thread guides 21, 22, 26, 28 together with the rotating thread guides 16, 17, 19 is shortest, which corresponds to the point A of the thread take-up or feed characteristic in Fig. 6. For the position of the parts which follows soon afterwards as indicated in Fig. 5, the three rotating thread guides 16, 17 and 19 have an elongating effect on the thread path. The position '5 is attained at the time when the needle bar '3 is at the upper dead point position which corresponds to point B in Fig. 6. The take-up effect which is common to all rotating thread guides 16, 17 and 19 lasts through a quarter turn, starting with the position in Fig. 2. From this moment all thread path sections between '28 and 21, respectively 21 and 22, become shorter again. This shortening, however, is offset by the continuing increase of the sections of the thread path 26'19:28 up to approximately a /a rotation, beginning with Fig. 2. Thus, the point C in accordance with Fig. 6 is attained. At the position of the parts in accordance with Fig. 3 which now follows (corresponding to point D of the thread feed characteristic) all rotating thread guides have a shortening effect on the thread path. If the needle bar it at its lower dead point the rotating structural unit has arrived at a position which is displaced by 180 with respect to point B. The effects of the thread guides 16 and 17 on the one hand and of the guide 19 on the other hand are at that moment equally large in an opposite sense so that a horizontal tangent is obtained of the thread feed characteristic in accordance with point E in Fig. 6. Further rotation leads again to the position in accordance with Fig. 2, respectively point A of Fig. 6.

In the thread take-up in accordance with the invention the thread path between thread guides 28 and 21, as well as 21 and 22, is increased and shortened twice for each rotation, but in the range between the thread guides 28 and 26, only once.

As shown in Fig. the connecting lines G and H between the fixed thread guides 21 and 28, respectively 21 and 22, intersect at a point F outside of the course K of "the rotating thread guides is avoided at the rotating thread guides 16 and 17. The

entire thread path in the take-up is guided in such a mannet that all rotating thread guides as seen progressively in the direction of thread pull are along one side of the thread path. In this manner the frictional forces which develop at the point of contact of the thread with the rotating thread guides act in the same direction upon the course of the thread in a manner that a tendency toward ioop formation within the thread take-up is avoided.

Having now described my invention with reference to the embodiment illustrated in the drawings, I do not wish to be limited thereto but what I desire to, protect by Letters Patent of the United States is set forth in the appended claims.

I claim:

1. In a sewing machine having a machine arm carrying a main shaft and having a machine head, aneedle bar reciprocably connected to said shaft and guided in said head, thread take-up means supported endwise of said shaft and including a unitary portion rotatably secured to said shaft and a stationary portion fixedly supported on said head in operative relationship to said rotatable unitary portion, said stationary portion presenting a plurality of thread guides disposed in fixed positions including at least two guides mounted on said stationary portion circumferentially of and on generally opposite sides of said rotatable portion and a guide mounted on the same side with one of said two guides at substantially the same distance as said one guide from a diametrical line extending through the other of said guides adapted to support the thread to define two sections of the thread path in acommon plane therebetween, and said rotatable portion presenting a plurality of thread guides mounted thereon in fixed positions relative to one another, rotatable at equal angular velocities in coaxial circular planes along said thread path, and including at least one rotatable guide operative at diiferent instants during one rotation to engage said two thread path sections in a manner to vary the length of said thread path.

2. In a sewing machine having a machine arm carrying a main shaft and having a machine head, a needle bar reciprocably connected to said shaft and guided in said head, thread take-up means supported endwise of said shaft and including a unitary portion rotatably secured to said shaft and a stationary portion fixedly supported on said head in operative relationship to said rotatable unitary portion, said stationary portion presenting a plurality of thread guides disposed in fixed positions including at least two guides mounted on said stationary portion circumferentially of and on generally opposite sides of said rotatable portion and a guide mounted on the same side with one of said two guides at substantially the same distance as said one guide from a diametrical line extending throughthe other of said guides adapted to support the thread to define two sections of the thread path in a common plane therebetween, and said rotatable portion presenting a plurality of thread guides mounted thereon in fixed positions relative to one another, rotatable at equal angular velocities in coaxial circular planes along said thread path, and including at least one rotatable guide operative at different instants during one rotation to engage said two thread path sections in a manner to vary the length of said thread path, and including one rotatable thread guide adapted to carry a portion of the thread in a different plane than said common plane.

3. In a sewing machine having a machine arm carrying a main shaft and having a machine head, a needle bar reciprocably connected to said shaft and guided in said head, thread take-up means supported endwise of said shaft and including a unitary portion rotatably secured to said shaft and a stationary portion fixedly supported on said head in operative relationship to said rotatable unitary portion, said stationary portion presenting a plurality of stationary thread guides disposed in fixed positions including at least two guides mounted on said stationary portion circumferentially of and on generally opposite sides of said rotatable portion and a guide mounted on the same side with one of said two guides at substantially the same distance as said one guide from a diametrical line extending through the other of said guides adapted to support the thread to define two sections of the thread path in a common plane therebetween, and said rotatable portion presenting a plurality of thread guides mounted thereon in fixed positions relative to one another, rotatable at equal angular velocities in coaxial circular planes along said thread path, and including at least one rotatable guide operative at different instants during one rotation to engage said two thread path sections in a manner to vary the length of said thread path, said two difierent thread path sections extending between different pairs of said stationary thread guides along straight lines intersecting each other externally of the largest circle of rotation of said rotatable guides thereby avoiding crossing of one said thread path sections over the other.

4. In a sewing machine having a machine arm carrying a main shaft and having a machine head, a needle bar reciprocably connected to said shaft and guided in said head, thread take-up means supported endwise of said shaft and including a unitary portion rotatably secured to said shaft and a stationary portion fixedly supported on said head in operative relationship to said rotatable unitary portion, said stationary portion presenting a plurality of thread guides disposed in fixed positions including at least two guides mounted on said stationary portion circumferentially of and on generally opposite sides of said rotatable portion and a guide mounted on the same side with one of said two guides at substantially the same distance as said one guide from a diametrical line extending through the other of said guides adapted to support the thread to define two sections of the thread path in a common plane therebetween, and said rotatable portion presenting a plurality of thread guides mounted thereon in fixed positions relative to one another, rotatable at equal angular velocities in coaxial circular planes along said thread path, and including at least one rotatable guide operative at different instants during one rotation to engage said two thread path sections in a manner to vary the length of said thread path, two of said rotatable thread guides being displaced substantially with respect to one another, and extending longitudinally in a direction substantially perpendicular with respect to the axis of rotation of said rotatable portion.

5. In a sewing machine having a machine arm carrying a main shaft and having a machine head, a needle bar reciprocably connected to said shaft and guided in said head, thread take-up means supported endwise of said shaft and including a unitary portion rotatably secured to said shaft and a stationary portion fixedly supported on said head in operative relationship to said rotatable unitary portion, said stationary portion presenting a plurality of stationary thread guides disposed in fixed positions including at least two guides mounted on said stationary portion circumferentially of and on generally opposite sides of said rotatable portion and a guide mounted on the same side with one of said two guides at substantially the same distance as said one guide from a diametrical line extending through the other of said guides adapted to support the thread to define two sections of the thread path in a common plane therebetween, and said rotatable portion presenting a plurality of thread guides mounted thereon in fixed positions relative to one another, rotatable at equal angular velocities in coaxial circular planes along said thread path, and including at least one rotatable guide operative at different instants during one rotation to engage said two thread path sections in a manner to vary the length of said thread path, and including one rotatable thread guide adapted to carry a portion of the thread in a difierent plane than said common plane, said two diflerent thread path sections extending between different pairs of said stationary thread guides along straight lines intersecting each other externally of the largest circle of rotation of said rotatable guides thereby avoiding crossing of one said thread path sections over the other, two of said rotatable thread guides being displaced substantially 180 with respect to one another, and extending longitudinally in a direction substantially perpendicular with respect to the axis of rotation of said rotatable portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,386,678 Backlin Oct. 9, 1945 FOREIGN PATENTS 500,130 Italy Nov. 17, 1954 

